Material for carburizing



Patented Jan. 8, 1924.

UNITED STATES Parana orrice.

GEORGE W. PRESSELL, OF PHILADELPHIA, PENNSYLVANIA, ASS IGNOR TO E. F. HOUGHTON & COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

No Drawing.

ening, which in addition to being of 1ela tively low cost and economical to uSe'ashall -be highly efficient; the invention contemplating a material of such a. nature as will insure the production of uniformly hardened" articles free from soft spots.

Another object of the invention is to provide a carburizingmaterial of such a nature as shall permitof its use with a relatively inexpensive filler for the carburizing pots.

I also desire to provide a novel method of applying a carburizing material to objects to be case hardened, as well as a novel method of case hardening which shall be convenient,- inexpensive and easy to operate.

In carrying out my' invention I prepare mycarburizing material in the form of a paste with which the steel to be hardened may be coated or into which the steel objects may be dipped. Said paste consists essentially of carbon dust. energizers such as nitrogenous products either with or without any or all of the carbonates of barium, sodium and calcium, with a binder such as molasses, sulphito liquor, or other organic carlmnacc'ous liquid. As typical of such nitrogenous products I may use cyanides, cyanimides, etc.

The mixture of the above ingredients in accordance with my inveiition has a, past-y consistency while retaining, certain of its liquid qualities and after the objects to be hardened have had this material applied in the form of a. coating, as above noted, by brushing, dipping or otherwise, they are placed in a carburizing pot upon a bed of carbon dust or pulverized coke. The spaces within or surrminding the coated steel objects are now filled with coke or other relatively inexpensive carbonaceous material and a'cover is applied to the pot, which-is liited in the customary manner. Thepot with its contents is placed in a carburizing furnace and exposed to a temperature of be tween 1600 and 1750 Fjfor a length of MATERIAL FOR CARBURIZING.

Application filed March 25-, 1922. Serial No. 546,807.

time dependent upon the depth of case hardening'desired.

Under these conditions the articles are hardened with the utmost certainty and uniformity inasmuch as the paste coating of :arbon and energizers is in direct contact with the steel and being in a substantially uniform layer thereon, as well as at a sub stantially uniform distance from all parts of the surface, results in a perfectly uniform, satisfactory product.

It is particularly to be noted that both the material described and the process of using it are relatively inexpensive and convenient, for all of such material applied to the steel objects is actually utilized in the hardening process and the space within the pot surrounding said objects is filled with inert material of relatively low value. There is thus none of the uneven or uncertain action which has hitherto characterized case hardening processes involving the repeated use of carburizing material which has been to a greater or less extent exhausted and which has become coi'itaminated with iron scale or tire clay.

Since the filling material used may be absolutely inert or may consist of coke which is used merely as a carbonaceous filler, the process depends solely upon the carburizing action of the paste or coating applied to the articles to be case hardened. Obviously the proportions in which the ingredients of the paste are used may be widely varied to suit. ilitl'crentcmiditions without departing from my invention, although l find that the standard proportions commonly employed in solid carbonaceous carburizing mixtures will give satisfactory results.

If desiredsand without departing from my invention, I-may omit the inert or other packing, merely coating the objects .to be case hardened and heating them to the required temperature in a closed pot.

I claim:

LA carburizing material of pasty consisteiicy consisting of a liquid vehicle, carbon and at least one carbonate.

2. A carburizing material in the form of a paste consisting of a carbonaceous liquid vehicle, carbon and an energizing material including at least one carbonate.

3. A carburizing inaterial in the form a paste consisting of a carbonaceous liquid vehicle, carbon and an energizing material including a nitrogenous substance and at least one carbonate.

6 4;, A carburizing material in the form of a paste consisting of a carbonaceous liqaid vehicle, carbon and an energizing material including at least one carbonate and a nitrogeneous material.

A carburizing material in the form of v a paste consisting of a carbonaceous liquid vehicle, carbon and a pluralitv of metallic carbonates.

GEORGE W. PRESSEBL 

